FIG. 2 illustrates an essential part of the structure of a compressor unit of a conventional closed type rotary compressor, and the reference numeral 1 indicates a casing. A rotary shaft 2 is accommodated in the casing 1, and this rotary shaft 2 is rotatably supported on a main bearing 3 and a sub-bearing 4. A cylinder 5 is held between the main bearing 3 and the sub-bearing 4, and a crank portion 6 is formed in the rotary shaft 2 between the main bearing 3 and sub-bearing 4. A ring-shaped roller 7 is fitted around the outer circumference of this crank portion 6. As the rotary shaft 2 rotates, the roller 7 is eccentrically rotated in the cylinder 5, and thereby the volume of the compressor chamber which is formed in the cylinder 5 is varied, so that the suction and compression of the coolant gas is carried out. In these events, coolant gas is sucked in the compressor chamber through a suction duct 8 whereas compressed gas issues out from a discharge duct not shown through the casing 1. The cylinder 5 is provided with a flat blade 9 for slidable movement in the radial direction of the rotary shaft 2. This blade 9 is spring biased by a compression spring 10 toward the axis of the rotary shaft 2. Accordingly, the edge of the blade 9 is always brought into contact with the outer circumferential surface of the roller 7. The eccentric rotation of the roller 7 causes the blade 9 to be reciprocally moved, so that oil accumulated in the bottom portion of the casing 1 is supplied to a predetermined portion to be lubricated through an oil pipe 11.
In such a closed type compressor, the temperature of the compressor is elevated due to compressed hot and high pressure coolant gas and heat generation of the motor during long running times. The hot and high pressure coolant gas and inner components of the casing 1 make direct contact, and therefore the structural parts are overheated during continuous running of the compressor, so that the compressor is deteriorated in reliability and volumetric efficiency.
To solve such a problem, there has been proposed an intermediate radiator system, in which compressed gas is introduced into an outer intermediate radiator for cooling, and then refluxed to the casing of the compressor to prevent overheating. Prior art of this type of compressor are disclosed and known in Japanese utility model examined publication No. 60(1985)-237184, Japanese utility model unexamined publication 62(1987)-18385, and Japanese patent unexamined publication 60(1985)-237184, for example.
Even in the case where compressed gas is once cooled through the intermediate radiator, a part, located within the casing, of the suction pipe which sucks coolant gas into the cylinder directly contacts hot and high temperature gas. This part is the part of the suction pipe which extends to and is connected with the cylinder. Thus, the temperature of coolant gas sucked into the cylinder is raised. This produces a problem in that the compressor is deteriorated in volumetric efficiency in spite of the cooling effect of the intermediate radiator.
Accordingly, an object of the present invention is to provide a closed type compressor which is capable of effectively preventing overheating of the compressor with an intermediate radiator by preventing direct contact between the portion, arranged within the casing, of the suction pipe and the hot, high temperature gas, whereby the problem of the prior art is overcome.